@Master-Spud
I now have a season of experience using the Dragonfly. I really like the unit. I bought it in a West Marine black friday sale for $499 in 2014 with Navionics Gold Maps.
The Gold Maps package included a coastal and a lakes chip. The lakes chip is supposed to cover popular lakes but it does not cover any of the lakes that I boat on. In June I purchased
Navionics Updates for $99. Updates is a 2GB $99 blank Navionics card that comes with the ability to download data to the chip for a year. You have to have an existing Navionics card to activate it. I bought the Updates in June and filled the card with map data from areas that I boat in in the Caribbean, my local lakes, the Gulf Coast Area and lakes in Texas that I plan to visit. Since I bought it in June I will be able to update the maps again just before the 2015 Bimini Fling. I like the fresh data but I am disappointed that the "Gold" maps that came with the unit did not cover my local lakes. I discussed this with Raymarine tech support. The agent said that he recommends buying without maps for inland lake usage and buying the regional maps. In my case having bought the unit with Gold Maps for less than normal pricing for the bare unit I came out on top despite spending an additional $99 for maps.
Twice this year, I have navigated 10 mile + trips on Lake Ouachita on moonless nights using the Dragonfly as my only guide. Lake Oauchita has more than 200 islands as well as ridges that extend close to the surface and standing timber. So nighttime boating is treacherous. I have found that the maps and representation on the Dragonfly are sufficiently accurate and timely that I can safely navigate around 20 mph on those moonless nights. The maps even include the buoys around the marinas.
The Dragonfly display is bright enough to work well on the sunniest days and dims low enough not to disturb night vision. Pressing the power button brings up a screen that has the brightness control selected. I often find myself using this method to adjust the brightness in the morning after having turned it down at night. I wish that the unit automatically adjusted the brightness.
I am not a fisherman so I have rarely used the down vision. I can say that it creates some pretty pictures of the bottom when you are going very slowly or sitting still. The
images on the Raymarine website are consistent with what I see but please note the speeds in the screen captures. For example
The unit provides a reliable depth reading under 30 MPH. Occasionally it will register depth at higher speeds but it always registers depth under 30 MPH which is way better than what the Norcross unit did.
When I bought my Dragonfly only the 5.7" version was available. There is a 7" version available now. The 5.7" is large enough for me and it could be awkward to have a larger unit on the dash. The 7" has slightly higher resolution at 800x640 vs 640x480 and might be an improvement for fishermen.